The withdrawal was first reported by AOL Fanhouse on Tuesday and independently confirmed by MMAWeekly.com sources. AOL also reported that Pat Miletich-trained Jason Reinhardt was likely to replace Karalexis, but MMAWeekly.com’s sources said that a replacement has yet to be locked down.

Zhang, fighting out of Beijing, is the first fighter from mainland China to fight for World Extreme Cagefighting.

“Tiequan is an excellent addition to our lightweight division,” WEC General Manager Reed Harris said. “He trains at a tremendous camp in Beijing and we are excited to have him compete with the best lighter weight fighters in the world.”

Boasting a perfect record of 16-0, Zhang trains with China Top Team, a group led by former Brazilian Top Team member Ruy Menezes.

A WEC featherweight title bout between current champion Jose Aldo and challenger Manny Gamburyan heads WEC 51 at the 1STBANK Center on Sept. 30 in Broomfield, Colo.